Carrier 040-420 User Manual

Page 50

Possible causes of failure:

3 .

5 .

High-Pressure Switch Open High-pressure switch for
each compressor is wired in series with 24-v power that
energizes compressor control relay. If high-pressure switch
opens during operation, compressor stops. This is
detected by microprocessor through the feedback
terminals.

DSIO-LV or DSIO-EXV Module Failure If a DSIO-LV

relay module relay fails open or closed, microprocessor
detects this, locks compressor off and indicates an error.
Wiring Errors If a wiring error exists causing CPCS,
CR, or feedback switch not to function properly, micro-
processor indicates an error.
Processor (PSIO) Failure

If hardware that monitors

feedback switch fails, or processor fails to energize re-
lay module relay to on, an error may be indicated.

NOTE: The control does not detect circuit breaker fail-
ures. If a circuit breaker trips on lead compressor in a
circuit, a low oil pressure failure is indicated. On the
other compressors, no failure is indicated.
Ground Fault Module on 130-2 10, 225, 250, 280, and
associated modular units (CGFA or CGFB) Open

Mod-

ule contacts are in lead compressor circuits, but ground
fault could be in any compressor in affected circuit.
Ground fault of any 040-l 10 and associated modular unit
compressor (field-supplied accessory on 040-060 and 070,
60 Hz units; standard on 070, 50 Hz and 80-l 10 and as-

sociated modular units) will cause a trip.

Checkout Procedure

Shut off main power to unit. Turn

on control power,

then step through subfunc-

tion

to proper compressor number (i.e., failure

code 5 is compressor

Next, energize the step. If

step works correctly, then failure code is caused by:

HPS (high-pressure switch) open

Misplaced feedback wire from

and J5 terminals

Ground wire and 24-v feeds reversed on one or more

points on

Compressor Alarm Circuit

For compressor Al

alarm circuit, processor closes contacts between termi-
nals 2 and 3 to start compressor. See Fig.

Safe-

ties shown to left of must be closed in order for power to
reach compressor control relay, and the feedback input ter-
minals on J3.

Failure of power to terminal 1 on

when contacts be-

tween 2 and 3 on J4 should be closed, causes a code 1

alarm.

Terminal 2 on is the other leg of the compressor Al

feedback channel. It is connected to the 24-v common.
NOTE: Similar connections for each compressor can be
lowed on the unit wiring diagrams located on the unit.
Code 9

Leaving water thermistor failure

Code 10

Entering water thermistor failure

If temperature measured by these thermistors is outside

range of -40 to 240 F (-40 to 116 C), unit shuts down after
going through a normal

Reset is automatic if tem-

perature returns to the acceptable range, and unit start-up
follows normal sequence. Cause of fault is usually a bad
thermistor, wiring error, or loose connection.

Code 19

Compressor Al suction sensor failure

Code 20

Compressor

suction sensor failure

On units with thermistors, if temperature measured by

these thermistors is outside the range of -40 to 240 F (-40
to 116 C), affected circuit shuts down after going through a

normal

Other circuit continues to run. Reset is

automatic if temperature returns to the acceptable range,

and circuit start-up follows normal sequence. Cause of

fault is usually a bad thermistor, wiring error or loose
connection.

On units with transducers, if the saturated suction tem-

perature is greater than the leaving water temperature plus

10” F (5.5 C) for more than 5 minutes, the affected circuit

shuts down (after going through normal pumpout). The re-
set is automatic if the saturated suction temperature returns
to the acceptable range and start-up follows the normal se-
quence. Cause of this fault is usually a bad transducer, a
wiring error, or a loose connection.
Code 21

Reset thermistor failure (applies only to installa-

tions having external temperature reset)

If temperature measured by this thermistor is outside range

to 240 F (-40 to 116 C), reset function is disabled

and unit controls to normal set point. If temperature returns
to the acceptable range, reset function is automatically en-
abled. Cause of this fault is usually a bad thermistor, wir-
ing error or loose connection.
Code 22

Code 23

Code 24

Code 25

Code 26
Code 27

Compressor A 1 discharge pressure
transducer failure

Compressor B 1 discharge pressure
transducer failure
Compressor A 1 suction pressure transducer
failure
Compressor B 1 suction pressure transducer
failure
Compressor Al oil pressure transducer failure
Compressor Bl oil pressure transducer failure

If output voltage of any of these transducers is greater

than 5 v, affected circuit shuts down without going through

process. Other circuit continues to run. Reset is

automatic if output voltage returns to the acceptable range,
and circuit start-up follows normal sequence. Cause of fault
is usually a bad transducer or a wiring error.

Code 28

Low transducer supply voltage

If transducer supply voltage is less than 4.5 v or greater

than 5.5 v, unit shuts down without going through
process. Reset is automatic if supply voltage returns to the

acceptable range, and circuit start-up follows normal se-

quence. Cause of fault is usually a faulty transformer, or
primary voltage is out of range.

The voltage supplied to the processor is polarized. When

checking for proper voltage supply, be sure to consider this
polarity. If voltage appears to be within acceptable toler-

ance, check to be sure the transformer supplying

is not

grounded. Grounding the supply transformer can result in
serious damage to the control system.
Code 29

Chilled water pump interlock switch open
(applies only if unit is configured for use with
a chilled water pump interlock).

Code can occur under any of these conditions:

1. Interlock switch fails to close

chilled water pump starts

within o n e minute after

2. Interlock switch opens during unit operation
3. Interlock voltage is detected, but unit is not configured

for interlock

4. Interlock voltage is outside its valid range

If any of these conditions occur, all compressors are dis-

abled and, if running, shutdown occurs without
Chilled water pump also shuts down. Reset is manual, with
LOCAL/ENABLE-STOP-CCN switch. Most probable cause
of this fault is shutdown or failure of chilled water pump to
start. Other possibilities are improper configuration or wir-
ing errors.